Audiovisual works, such as movies, include video accompanied by a soundtrack. A video may be associated with multiple soundtracks, such that the video can be displayed with different soundtracks in different regions and/or contexts. Further, some methods enable a viewer to select from multiple soundtracks when viewing an audiovisual work in a private or personal setting. For example, DVDs may be encoded with multiple soundtracks, and television broadcasts may include an alternate soundtrack using a second audio program (SAP) scheme.
In contrast, when a video is shown to an audience, such as in a movie theater, one soundtrack must be selected and played. For example, an English soundtrack may be played when a movie is shown to a predominantly English-speaking audience, whereas a Spanish soundtrack may be played when the movie is shown to a predominantly Spanish-speaking audience. However, an audience may not be homogeneous, and audience members who do not understand the language of the soundtrack played may have difficulty understanding the content of the video. Further, while supplemental audio content (e.g., commentary) may be of interest to some, playing such content to an entire audience may be undesirable.
In addition, even in the context of private viewing, existing schemes such as SAP may be limited by the quantity of secondary soundtracks that can be provided. For example, such schemes may enable a soundtrack to be broadcast in two languages, but may not support transmitting the soundtrack in a third language or transmitting a supplemental (e.g., commentary) soundtrack in addition to the two languages. Moreover, existing schemes for providing secondary soundtracks may enable such soundtracks to be provided only a publisher or broadcaster of an audiovisual work, such that listening to a secondary soundtrack from a third party may require the viewer to manually synchronize the desired soundtrack with the audiovisual work.